High Country News: Last fall, a Viking washed up on my doorstep. His name was Soren Hermansen. For the past 10 years, he has spearheaded one of the most audacious experiments in the world: the attempt of 4,000 people living on the small Danish island of Samso to liberate themselves from fossil fuel. A few weeks after being anointed an Environmental Hero by Time, Soren came to America on a speaking tour with his wife, Melane, an artist and photographer. Everyone wants to hear the story of Samso. …